5.15-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ Upstream commit 469308552ca4560176cfc100e7ca84add1bebd7c ]
ip4_dst_hoplimit() must use RCU protection to make sure the net structure it reads does not disappear.
Fixes: fa50d974d104 ("ipv4: Namespaceify ip_default_ttl sysctl knob") Signed-off-by: Eric Dumazet edumazet@google.com Reviewed-by: Kuniyuki Iwashima kuniyu@amazon.com Link: https://patch.msgid.link/20250205155120.1676781-3-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- include/net/route.h | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/include/net/route.h b/include/net/route.h index 30610101ea14f..036e3ee3b856b 100644 --- a/include/net/route.h +++ b/include/net/route.h @@ -357,10 +357,15 @@ static inline int inet_iif(const struct sk_buff *skb) static inline int ip4_dst_hoplimit(const struct dst_entry *dst) { int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT); - struct net *net = dev_net(dst->dev);
- if (hoplimit == 0) + if (hoplimit == 0) { + const struct net *net; + + rcu_read_lock(); + net = dev_net_rcu(dst->dev); hoplimit = READ_ONCE(net->ipv4.sysctl_ip_default_ttl); + rcu_read_unlock(); + } return hoplimit; }